Relationship between the water dynamics and the internal dynamics of actin studied by quasi-elastic neutron scattering

中性子準弾性散乱によるアクチンの水和水ダイナミクスと内部ダイナミクスの関係の研究

藤原 悟; Plazanet, M.*; 小田 俊郎*

Fujiwara, Satoru; Plazanet, M.*; Oda, Toshiro*

Thermal fluctuations, or dynamics, of the protein are indispensable for the structural changes that make the protein function. Since the proteins sit in an aqueous environment, ultimate understanding of the protein functions requires understanding of the dynamics of the proteins including the hydration water. We have been investigating the dynamics of the protein, actin. Here we employed quasi-elastic neutron scattering (QENS) to characterize the dynamics of the hydration water around actin under various structural states. The QENS spectra of actin in DO and HO were measured with the instrument IN5 in the Institut Laue-Langevin, Grenoble, France. The spectra of the hydration water were extracted from the obtained spectra. Analysis of these spectra provided the parameters characterizing the hydration water dynamics such as the diffusion coefficients and the residence times. Comparison with the internal dynamics of actin showed that the hydration water dynamics and the internal dynamics are indeed correlated. Possible dependence of the hydration water dynamics of salt concentration is also suggested.